A polymer containing an aldehyde group or a ketone group (hereinafter, also referred to as an “aldehyde/ketone-containing polymer”) can be used for bonding a bioactive molecule containing a functional group such as an amino group, an imino group, or a hydrazide group by forming a pH sensitive Schiff base.
Further, the aldehyde group-containing polymer can also be used for core crosslinking of cationic polypeptides. Therefore, the aldehyde/ketone-containing polymer has been attracting attention particularly in the pharmaceutical field as a carrier that delivers a drug.
A method of introducing an aldehyde to a polymer, a method of performing RAFT polymerization on 4-vinylbenzaldehyde to obtain an aldehyde-introduced polymer has been known (for example, NPLs 1 to 4).